<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="js/vue.js"></script>
</head>
<body>

    <div id="app">
            <button @click="isShow = !isShow">切换</button>
            <div 
                style="width:400px;height:400px;background:red;"
                v-if="isShow"
            ></div>
            <div v-else style="width:200px;height:200px;background:blue;"></div>
    </div>
    <script>
        let vm = new Vue({
            el:"#app",
            data:{
               isShow:true
            }
        })
    </script>
</body>
</html>